I actually really like Rimmel's fix and perfect pro (there are two the one that isn't "pro" was junk IMO). This primer helped me out SO much for my brothers wedding when I was on accutane and my skin was flakey. I seems to moisturize and mattify at the same time. We were out in the hot sun all day and it kept my makeup from melting off. I only use primer on special occasions though but this was better then some of the high end primers I have tried.
I don't wear primer often, but I did like a Korres sample that I recently tried. I also have heard really great things about Hourglass, but have yet to try it myself.
I like the Korean brand, Holika Holika. They have a product called Miracle Real Skin Finish, which is a multi-purpose product. You can wear it alone or as a primer. It gives my skin a soft focus look which you can wear alone on a light day.